Can't give prognosis on so little data
Your EMS on supraspinatus should slowly be increased to up to six hours continuous and is for pain control not functon. If you have lost external rotation you can expect to have no elevation past 90 degrees and SHOULD NOT be trying to range past this. Before ranging make sure you approximate the shoulder to eliminate impingement and levering on ligaments. Do not do pulley work or have the patient do auto assisted flexion into elevation. This will only increase pain and cause further loss of range. Always have the arm supported when sitting . In lying never lie directly on the shoulder but rather pull the shoulder forward so weight bearing is on the scapula. A quarter turn off supine is recommended rather than fully over on the side. In supine supporting the arm in some abd, flex, and ext rot is ideal.
Its not unusual for fatique to be the limiting factor initially but this usually improves.
Rather than all the other EMS functional activity would probably be better.

highmode